Liquid hydrocarbon fuel compositions



gram? 3,070,420 Patented Dec. 25, 1962 mourn HYDRGQ-aithfiri CGMPQSETifiN Elizabeth H. Fareri and .iohn P. ieliegrini, 31"., Pittsburgh,

Pa., assignors to Guif Research & Deveiopment 6on1- pany, Pittsburgh, E11,, a corporation of Deiaware No Drawing. Filed June 6, 1960, er. No. 33,934

11 Claims. (Ci. 44-62) This invention relates to liquid hydrocarbon distillate fuels and more particularly to such fuels that have reduced deposit-forming tendencies and that contain small amounts of oil-soluble copolymers of higher allzyl esters of acrylic or methacrylic acid and salts of aliphatic monoamines and acrylic or methacrylic acid.

Uncompounded liquid hydrocarbon distillate fuels frequently tend to form troublesome deposits under service conditions. For example, fuel oils of No. 2 grade and heavier that have an Aii gravity less than 34, that is, fuel oils relatively rich in aromatic components, frequently tend to promote substantial smoking and formation of soot deposits during combustion, even when conditions favorable to efiicient combustion of the fuel are employed.

Combustion gas turbine fuels, particularly aviation turbine fuels, that is, jet fuels, also have been found to form deposits during use, which deposits tend to clog the fuel nozzles or orifices by way of which the fuel is introduced into the combustion chambers of engines in which the fuel is being consumed. The formation of these de posits is attributed at least in part to the use of the fuel as a cooling medium to remove heat from lubricating oil that has absorbed heat developed by the compression of combustion air, fuel combustion, and friction. In such use the fuel is subjected to service temperatures, of the order of 300 to 400 F. for substantial periods of time, and to even higher temperatures, of the order of 500 F. or more for shorter periods of time in the area of the fuel nozzles or orifices. Under such temperature conditions, the less stable components of the fuel tend to undergo degradation as a result of polymerization, oxidation, and thermal decomposition reactions and to form solid or semi-solid deposits that interfere with proper functioning of jet engines.

By way of further example, motor gasolines having a 50 percent AST M distillation point less than about 235 F., and es ecially below about 220 F, have been found to promote stalling of internal combustion engines prior to warm-up in a cool, humid atmosphere, by deposition of ice particles, derived from frozen atmospheric moisture, on the carburetor throttle plates of such engines. These deposits tend to restrict how of air through the carburetor throat during idling, whereby stalling occurs.

The present invention relates to liquid hydrocarbon fuels that have reduced deposit-forming tendencies whereby such fuels are rendered more suitable for combustion in the furnaces or engines in which the fuel is normally consumed. It has been found that the deposit-forming tendencies of liquid hydrocarbon distillate fuels can be reduced by incorporation therein of a small amount of an oil-soluble copolymer of (A) a monomeric alkyl ester of an acid selected from the group consisting of acrylic and methacrylic acids whose alkyl ester substituent contains 8 to 18 carbon atoms, and (B) a monomeric salt formed from substantially equivalent proportions of an acid selected from the aforesaid group and an amine having as at least one N-substituent an aliphatic hydrocarbon radical containing 8 to 18 carbon atoms, and as the other N-substituents members selected from the group consisting of hydrogen, aliphatic hydrocarbon radicals containing 1 to 18 carbon atoms, and alkylol groups containing 1 to 4 carbon atoms, said monomeric amine salt and said monomeric alkyl ester being copolymerized in a weight ratio in the range of about 0.03:1 to 1:1, and preferably in the range of about 0.05:1 to 0.75:1. Polymers prepared from the above-indicated ratios of monomers will usually be characterized by a nitrogen content in the range of about 0.03 to 3.5 percent by weight. We normally prefer to employ copolymers containing at least about 0.2 percent and preferably about 0.2 to 2 percent nitrogen, but copolymers having greater and lesser nitrogen content can be used. Specific examples of copolymers with which excellent results can be obtained are the 1:9 weight ratio copolymer of monomeric oxo-octylammonium methacrylate and lauryl methacrylate, the 1:9 Weight ratio copolymer of monomeric di(oxo-octyl)ammonium methacrylate and monomeric lauryl methacrylate, the 3:7 weight ratio copolymer of monomeric di(oxooctyl)ammonium methacrylate and monomeric lauryl methcrylate and the 1:9 weight ratio copolymer of monomeric di(oxo-octyl)hydroxyethylammonium methacry late and monomeric lauryl methacrylate. Examples of other copolymers whose use is included by the invention are the 1:19 weight ratio copolymer of monomeric di- (oxo-octyl)hydroxyethylammonium methacrylate and monomeric lauryl methacrylate and the 2:8 weight ratio copolymer of monomeric di(oxo-octyl)hydroxyethylammonium methacrylate and monomeric lauryl methacrylate. Examples of still other copolymers the use of which is included by this invention are the 0.05:1, 01:1, 05:1, and 1:1 weight ratio copolymers of monomeric octylammonium, dioctylarnmonium, trioctylammonium, lauryl ammonium, octadecylammonium, octadecenylammonium acrylates and methacrylates and monomeric n-octyl, lauryl, oxo-octyl, 2-ethylhexyl, oxo-tridecyl and n-hexa decyl acrylates and methacrylates. We prefer to employ the copolymers in hydrocarbon distillate fuels in proportions of about 10 to 50 pounds of copolymer per 1,000 barrels of distillate fuel, but other proportions can be used. For example, the copolymers can be employed in amounts of as little as 2.5 pounds per thousand barrels of fuel or up to 0.1 percent by weight of the feul, that is, about 300 pounds per thousand barrels of distillate fuel.

The copolymers disclosed herein can be prepared in any convenient way. For example, they can be prepared by reacting the desired monomers in weight ratios of about 0.03 to 1 part by weight of the substantially neutral ammonium acrylate or methacrylate, that is, the salt formed by reaction of substantially equivalent proportions of amine and acrylic or methacrylic acid, for each part by weight of the ester monomer, in the presence of a diluent, preferably a solvent, such as toluene, benzene, ethyl acefate or other solvents having similar chain transfer activity, at a temperature in the range of C. to C. preferably 25 C,. to 150 C., in the presence of a few hundredths percent to 2 percent, preferably 0.2 to 1.0 percent, of a free radical catalyst such as benozyl peroxide, lauroyl peroxide, or alpha, alpha-azodiisobutyronitrile, preferably in the substantial absence of oxygen, until the rate of formation of larger polymer molecules has declined substantially, usually after about 3 to 35 hours or longer, as determined by periodic sampling of the reaction mixture and observing the viscosity thereof.

The preferred ester monomers from which the copolymers disclosed herein are prepared can be represented by the general formula: CH =CRCOOR where R is hydrogen or a methyl radical and R is a straight or branched chain alkyl group containing 12 to 18 carbon atoms, such as lauryl, oxo-tridecyl, n-hexadecyl, or noctadecyl. The preferred ammonium salt monomers from which the herein-described copolymers are prepared can be represented by the general formula:

where R is as defined above,

RI N RII is a secondary or tertiary amine, R is an alkyl, alkenyl, or alkadienyl radical containing 8 to 18 carbon atoms, such as lauryl, myristyl, n-hexadecyl, n-octadecyl, noctadecenyl, or n-octadecadienyl, and li'fis a member selected from the group consisting of aliphatic hydrocarbon radicals containing 1 to 18 carbon atoms such as methyl, propyl, butyl, or any'of those mentioned in the description of R, and alkylol groups containing 1 to 4 carbon atoms, such as ethylol and propylol radicals, and R is hydrogen or a radical of the same kind as R".

Neither the alkyl ester substituents of the ester monomers nor the N-substituents of the ammonium salt monomers need be pure; instead these substituents can comprise mixtures of radicals derived from commercially available materials. For example, the alkyl ester substituents of the ester monomers can be derived from a mixture of synthetically produced, isomeric, branched-chain alcohols of the kind produced by the well-known oxo-synthesis process. Alternatively, the ester substituents can be derived from a mixture of fatty alcohols obtained from coconut oil fatty acids or tallow fatty acids or other acids derived from naturally occurring fats or oils. Similarly, the N- substituents of the nitrogenous monomer can comprise a mixture of alkyl, alkenyl, and/or alkadienyl groups derived from commercial materials such as coconut oil fatty acids, soya fatty acids, or tallow fatty acids. When the substituents referred to above are derived from natural fats and oils, the mixed radicals will comprise homologous mixtures of alkyl or alkyl and alkenyl, or alkyl, alkenyl, and alkaldienyl radicals containing an even number of carbon atoms from 8 to 18. The ester substituents of the ester monomer and the N-substituents of the ammonium salt monomer can also be substituted, if desired, with nonhydrocarbon substituents, such as halogens, hydroxyl, sulfhydryl, carbonyl, amino, or the like that do not adversely affect the oil solubility or deposit-inhibiting characteristics of the salts.

The preferred copolymers of this invention are copolymers of the above-indicated preferred monomers in weight ratios in the range of about 0.05 to 0.75 part by weight of ammonium salt monomer to 1 part by Weight ester monomer.

The average molecular weight of the copolymers disclosed herein will normally be greater than about 2,000, and is preferably greater than about 7,500, as determined by conventional methods. Usually the molecular weights of the copolymer will not exceed about 500,000, but the molecular Weights can be greater. In fact, copolymers having molecular weights of any upper limit can be used, provided that the molecular weight is not so great as to render the copolymer insoluble in the liquid hydrocarbon fuel distillates.

The copolymers disclosed herein can be employed in a wide variety of normally liquid hydrocarbon fuel distillates. For example, they can be employed in motor gasoline of both premium and regular grades, aviation gasoline, furnace oils, such as those used in ordinary heating installations, of which No. 2 fuel oil is an example, light and medium diesel fuel, aviation turbine fuel, and the like. Motor gasolines, aviation gasolines, distillate fuel oils and diesel fuels are defined in the ASTM Standards on Petroleum lroducts and Lubricants under the respective specifications ASTM D-439, D-9l0, D396, and

tors.

t- D-975. Aviation turbine fuels of the type included by the present invention are liquid hydrocarbon mixtures of the kind disclosed by the following specifications: MILi 5161B (Referee LIP-4 Fuel), MlLl5624D (JP4, JP- 5 Fuel), MIL-F-25656 (P6 Fuel), MlLF-25524A (Thermally Stable Fuel), MlLF-25558B (RI-1 Fuel), MlL-R25576B (RP-l Fuel), and American Airlines Specification No. M64A.

The copolymers disclosed herein are useful when employed in liquid hydrocarbon fuel distillates in amounts sufficient to reduce a deposit-forming tendency of the oils. The copolymers disclosed herein are not necessarily exactly equivalent in effectiveness, and all of the distillate fuels are not necessarily equivalently responsive thereto; therefore, the optimum proportions of copolymer may vary somewhat in accordance with these fac- Usually, some improvement will be obtained by the use of as little as about 2.5 pounds of copolymer per thousand barrels of fuel and a major improvement will be obtained by the use of 10 to 25 pounds per thousand barrels. Usually, we prefer to employ the copolymers in proportions not exceeding about 50 pounds per thousand barrels, but in some instances it may be desired to employ the copolymers in proportions as great as 300 pounds per thousand barrels. Normally, no additional advantage Will be obtained from the standpoint of inhibiting deposit formation by the use of greater proportions.

The herein-described copolymers can be incorporated in the hydrocarbon fuel distillates in any convenient way. For example, they can be added directly to the fuel oil in the form of concentrated solutions in solvents such as toluene, kerosene, or light lubricating oil in order to facilitate blending. If desired, the copolymers can be added to the fuels in conjunction with other compatible addition agents that are capable of improving one or more properties of the fuels. In instances of blended fuels, the copolymers can be added to one of the fuel components prior to blending. Some stirring of the fuel during admixture with the copolymers, with or without moderate heating, may be desirable to facilitate rapid formation of a homogeneous mixture, but stirring is not I absolutely necessary.

The effectiveness of the herein-disclosed copolymers to inhibit deposition of solids from distillate fuels has been demonstrated in several ways. Thus, in accordance with one test, a representative member of the class of copolymers whose use is included by this invention was incorporated in a sample of a No. 2 fuel oil, and the thus-compounded fuel oil was subjected to a full-scale, one-day smoke test in a domestic oil burner (Timken Model OBC-llO, oil-boiler). Conventional burner controls were associated with the test apparatus in conjunction with electrical timer relays to provide 20-minute on and 10-minute off cycles of burner operation. After permitting a warm-up of at least one 20-minute on cycle of burner operation with maximum combustion air, smoke spot number and carbon dioxide content reading were taken on the flue gas at the middle of the on" phases for several cycles using different air gate settings to regulate the quantity of combustion air, to determine the burner setting most conducive to clean combustion. Changes of gate setting were made during burner off phases of the cycle. Smoke spot readings were obtained by withdrawing flue gas from a sampling probe installed in the chimney pipe through a disc of a No. 4 Whatrnan filter paper one inch in diameter for two minutes. A vacuum pump was used to maintain a pressure differential of 2% inches Hg across the disc. The smoke spot rating was determined by means of a photocell meter that had been calibrated by a Bacharach- Shell smoke spot chart graduated in increasing shades of black ranging from 0 (clean disc) to 9 (black disc) as the standard. CO readings were obtained by Withdrawing flue gas through a sampling probe installed in the u chimney pipe in accordance with the United States Department of Commerce Bulletin CA104-46, and by analyzing the thus-withdrawn fine gas for percent CO in an Orsat-type flue gas analyzer.

The No. 2 fuel oil employed in the above-described test Was a blend of 17.5 pe r6211 by volume of a mildly hydrogenated West Texas straight-run and 82.5 percent by volume of a fiuid catalytically cracked No. 2 fuel oil distillate having an API gravity of 29.6 and an aro matics content of 42 percent by weight.

The copolymer employed in the test was a 1:9 weight ratio copolymer of monomeric oXo-octylammonium methacrylate and monomeric lauryl methacrylate. A 33% percent (weight) oil concentrate of this copolymer had a nitrogen content of 0.23 percent by weight, a total acid number of 8.70, a total base number of 5.39, and a saponification number of 17.08. The copolymer was prepared by adding 10.33 grams of glacial methacrylic acid to 15.84 grams of oxo-octylamine in 130.0 grams of toluene. To the resulting clear solution was added 235.5 grams of lauryl methacrylate and 1.56 grams of alpha, alpha-azo-diisobutyronitrile. The reaction mixture was stirred and heated at about 68 to 72 C. for 3 /2 hours. During the next 1 /4 hours, the temperature was raised to 106 C. Nitrogen was bubbled through the reaction mixture throughout the reaction period. At the end of the reaction period, the reaction mixture, which was very viscous, was diluted with 523.4 grams of an SAE W lubricating oil. Toluene was then removed under reduced pressure with heating, yielding a lubricating oil solution containing 33 /3 percent by Weight of the copolymer named above.

The smoke spot numbers obtained in the abovedescribed test under the conditions found to be most The results set forth in the preceding table clearly demonstrate the effectiveness of the copolymers of the class whose use is described herein to reduce smoke and soot deposits in actual operation in domestic fuel oil burners, notwithstanding the use of a rather clean-burning base fuel and the use of cleanest burning combustion conditions.

The effectiveness of the copolymers of the class whose use is included by the present invention to inhibit formation of deposits in combustion gas turbine engine fuels has also been demonstrated. In accordance with the test procedure employed, separate samples of an aviation turbine fuel containing representative copolymers of the class disclosed herein were subjected to the CFR Fuel Coker test procedure described in ASTM Standards on Petroleum Products and Lubricants for 1959, ASTM D166059T. In accordance with this test method, aviation turbine fuels are subjected to flow conditions and temperature stresses similar to those existing in jet aircraft engines. The test apparatus comprises a fuel oil system containing two heated sections: (1) a preheater section that simulates the hot fuel line sections of a jet engine as typified by an engine fuel-lubricating oil cooler and (2) a filter section that simulates the nozzle or fuel inlet area of the combustion zone of an aircraft jet engine Where fuel degradation products may be trapped. A precision sintered, stainless steel filter is employed in the filter section to trap fuel degradation particles formed during the test. The extent of the buildup of fuel degradation particles in the filter section is indicated by the pressure differential across the test filter and this is used as an index of the high temperature stability of the aviation turbine fuel. In carrying out the test, the temperature of the fuel at the outlet of the preheater section was maintained at 410 F. and the filter section was maintained at 500 F. During the test, the fuel was caused to fiow through the test apparatus at the rate of six pounds per hour and the duration of the test was five hours.

The test fuel, hereinafter referred to as Aviation Turbine Fuel A, comprised a blend of petroleum distillates having the following properties:

Aviation turbine fuel A Gravity, APT 43.6 Existent gum, mg./100 ml 1.6 Potential gum, rug/100 ml 5.2 Sulfur, L, percent 0.054

Mercaptan sulfur, percent 0.001

Three different copolymers were employed in the test. The first copolymer was a 1:9 weight ratio copolymer of monomeric di(oxo-octyl)ammonium methacrylate and monomeric lauryl methacrylate. The second copolymer was 1:9 weight ratio copolymer of monomeric di-(oxooctyl)hydroxyethylammonium methacrylate and mono meric lauryl methacrylate as a 33 /3 percent by weight concentrate in lubricating oil having a nitrogen content of 0.14 percent by weight, a total acid number of 5.21, a total base number of 5.01, and a saponification number of 21.65. The third copolymer was a 3 :7 weight ratio copoly mer of monomeric di-(oxo-octyl)ammonium methacrylate and monomeric lauryl methacrylate. The results of the foregoing tests were as set forth in the following table:

Table B 1 Average of two determinations.

The results set forth in the preceding table demonstrate the marked reduction in deposit-forming tendencies of jet fuels imparted by the copolymers disclosed herein. The results obtained in Test Run No. 3 above also indicate the especial effectiveness of copolymers derived from monomeric amine salts of tertiary amines, especially tertiary amines containing an alkylol group as an N-substituent.

The ability of the copolymers of the class disclosed herein to reduce the stalling tendencies of gasolines that normally promote engine stalling by formation of ice deposits on carburetor surfaces was demonstrated by subjecting gasoline samples containing representative members of the class of copolymers whose use is included by u the present invention to a Mock Fuel System bench-scale test. In accordance with this test, test gasoline at about 50 F. together with air at ambient temperature, that is, 70 to 80 F., and at about 90 percent relative humidity, is introduced at controlled rates to a glass vaporizing chamber held at an absolute pressure of six inches of mercury, and the time required for icing to occur on a brass tube positioned in the vaporizer chamber is observed. Performance of the test fuel was determined by comparing the time for ice formation on the brass tube with that required for the uninhibited fuel under the same test conditions. Test results are expressed in terms of the isopropanol equivalent concentration required in the uninhibited fuel to obtain the same anti-icing action, isopropanol being a well-known commercially used carburetor anti-icing additive. The fuel employed in the test was a gasoline having a 50 percent ASTM distillation point of 200 F.

Three different copolymers were employed in the above-described tests. The first copolymer was a 1:9 weight ratio copolymer of monomeric di(oxo-octyl) ammonium methacrylate and lauryl methacrylate having a nitrogen content of 0.51 percent by weight, a total acid number of 17.23, a total base number of 11.80, a saponification number of 13.53, an intrinsic viscosity at 77 F. in toluene of 0.12 deciliter per gram and a molecular weight of 130,000 as determined by the shear method of F. Bueche and S. W. Harding, Journal of Polymer Science, vol. XXXII, pages 177-186 (1958), with application of an appropriate instrument calibration constant. The secand copolymer was a 3:7 weight ratio copolymer of monomeric di(oXo-octyl) ammonium methacrylate and lauryl methacrylate having a nitrogen content of 1.34 percent by weight, a total acid number of 58.83, a total base number of 44.45, and a saponification number of 85.43. The third copolymer was the 1:9 weight ratio copolymer of monomeric oXo-octylammonium methacrylate and lauryl methacrylate described above in connection with the combustion test involving No. 2 fuel oil.

The results of the above-described tests were as follows:

From the results presented in the foregoing table it will be seen that the copolymers of the class described herein are capable of effecting a marked improvement in the carburetor icing tendencies of gasolines that normally tend to promote carburetor icing.

The specific embodiments set forth hereinabove are illustrative only, and good results can be obtained by substitution in the fuel compositions of the preceding embodiments of the same or equivalent proportions of other copolymers of the class disclosed herein. For example, there can be substituted with good results the 0.05:1, 0.1:1, 0.5:1, and 1:1 weight ratio copolymers of monomeric octylammonium, dioctylammonium, trioctylammonium, laurylammonium, octadecylammonium, octadecenylammonium acrylates and methacrylates, and monomeric n-octyl, lauryl, 2-ethylhexyl, oXo-tridecyl, and n-hexadecyl acrylates and methacrylates.

It will be understood that other addition agents adapted to improve one or more properties of liquid hydrocarbon distillate fuels can be incorporated in the compounded fuel compositions of this invention. For example, there can be added antiknock agents, lead scavengers, antipreignition agents, antioxidants, corrosion inhibitors, dispersants, cetane number improvement agents, other combustion improvers, ignition promoters, and the like.

Numerous modifications and variations of the invention as herein set forth can be resorted to Without departing from the spirit or scope of the invention. Accordingly, only such limitations should be imposed as are indicated in the claims appended hereto.

We claim:

1. A liquid hydrocarbon fuel composition comprising a major amount of a liquid hydrocarbon fuel distillate and a small amount, sufficient to reduce the deposit-forming tendencies of the fuel, of an oil-soluble copolymer of (a) a monomeric alkyl ester of an acid selected from the group consisting of acrylic and methacrylic acids whose alkyl ester substituent contains 8 to 18 carbon atoms, and (b) a monomeric salt formed from substantially equivalent proportions of an acid selected from the aforesaid group and an amine having as at least one N-substituent an aliphatic hydrocarbon radical containing 8 to 18 carbon atoms, and as the other N-substituents members selected from the group consisting of hydrogen, aliphatic hydrocarbon radicals containing 1 to 18 carbon atoms and alkylol groups containing 1 to 4 carbon atoms, said monomeric amine salt and said monomeric alkyl ester being copolymerized in a weight ratio in the range of about 0.03:1 to 1:1. 7

2. The fuel composition of claim 1 Where the nitrogen content of the copolymer is in the range of about 0.03 to 3.5 percent by weight of the copolymer.

3. The fuel composition of claim 1 where the nitrogen content of the copolymer is in the range of about 0.2 to 2 percent by weight of the copolymer.

4. The fuel composition of claim 1 where said copolymer is present in the amount of about 2.5 to 300 pounds per 1,000 barrels of said distillate.

5. The fuel composition of claim 1 Where said copolymer is present in the amount of about 10 to 50 pounds per 1,000 barrels of said distillate.

6. The fuel composition of claim 1 where said alkyl ester substituent contains 12 to 18 carbon atoms and said amine has as at least one N-substituent an aliphatic hydrocarbon radical containing 8 to 18 carbon atoms, as another N-substituent a member selected from the group consisting of alkylol groups containing 1 to 4 carbon atoms and aliphatic hydrocarbon radicals containing 1 to 18 carbon atoms, and as the remaining N-substituent a member selected from the group consisting of hydrogen and radicals of the same kinds as the second-mentioned N-substituent.

7. A liquid hydrocarbon fuel composition comprising a major proportion of a liquid hydrocarbon distillate selected from the group consisting of gasoline motor fuel and distillate fuel oils higher boiling than gasoline, and a small amount, sufficient to reduce the deposit-forming tendencies of said liquid hydrocarbon fuel distillate, of an oil-soluble copolymer of (a) a monomeric alkyl ester of an acid selected from the group consisting of acrylic and methacrylic acid whose alkyl ester substituent contains 8 to 18 carbon atoms and (b) a monomeric salt formed from substantially equivalent proportions of an acid selected from the aforesaid group and an amine having as at least one N-substituent an aliphatic hydrocarbon radical containing 8 to 18 carbon atoms, and as the other N-substituents members selected from the group consisting of hydrogen, aliphatic hydrocarbon radicals containing 1 to 18 carbon atoms and alkylol groups containing 1 to 4 carbon atoms, said monomeric amine salt and said monomeric alkyl ester being copolymerized in a weight ratio in the range of about 0.03:1 to 1:1.

8. A liquid hydrocarbon fuel composition comprising a major proportion of a distillate fuel oil higher boiling than gasoline and a small amount, sufii-cient to reduce the deposit-forming tendencies, of an approximately 1:9 weight ratio copolymer of monomeric di(oXo-octyl) ammonium methacrylate and monomeric lauryl methacrylate.

9. A liquid hydrocarbon fuel composition comprising a major proportion of a distillate fuel oil higher boiling than gasoline and a small amount, sufficient to reduce the deposit-forming tendencies, of an approximately 1:9 weight ratio copolymer of monomeric di(oxo-octyl)-hydroxyethylammonium methacrylate and monomeric lauryl methacrylate.

10. A liquid hydrocarbon fuel composition comprising a major proportion of a distillate fuel oil higher boiling than gasoline and a small amount, sufiicient to reduce References Cited in the file of this patent UNITED STATES PATENTS 2,892,690 Lowe et al. June 30, 1959 

1. A LIQUID HYDROCARBON FUEL COMPOSITION COMPRISING A MAJOR AMOUNT OF A LIQUID HYDROCARBON FUEL DISTILLATE AND A SMALL AMOUNT, SUFFICIENT TO REDUCE THE DEPOSIT-FORMING TENDENCIES OF THE FUEL, OF AN OIL-SOLUBLE COPOLYMER OF (A) A MOMONERIC ALKYL ESTER OF AN ACID SELECTED FROM THE GROUP CONSISTING OF ACRYLIC AND METHACRYLIC ACID WHOSE ALKUL ESTER SUBSTITUENT CONTAINS 8 TO 18 CARBON ATOMNS, AND (B) A MONOMERIC SALT FORMED FROM SUBSTANTIALLY EQUIVALENT PROPORTIONS OF AN ACID SELECTED FROM THE AFORESAID GROUP AND AN AMINE HAVING AS AT LEAST ONE N-SUBSTITUENT AN ALIPHATIC HYDROCARBON RADICAL CONTAINING 8 TO 18 CARBON ATOMS, AND AS THE OTHER N-SUBSTITUENTS MEMBERS SELECTED FROM THE GROUP CONSISTING OF HYDROGEN, ALIPHATIC HYDROCARBON RADICAL CONTAINING 1 TO 18 CARBON ATOMS AND ALKYOL GROUPS CONTAINING 1 TO 4 CARBON ATOMS, SAID MONOMERIC AMINE SALT AND SAID MONOMERIC ALKYL ESTER BEING COPOLYMERIZED IN A WEIGHT RATIO IN THE RANGE OF ABPUT 0.03:1 TO 1;1. 